The present invention relates to improvements in paint spray booths of the type disclosed in U.S. Pat. No. 3,932,151, issued Jan. 13, 1976, the disclosure of which application is incorporated herein by reference. Said application discloses a paint spray booth for removing excess atomized paint from the air in the vicinity of a paint spraying operation. The spray booth comprises an enclosure having a working or spray painting area, an exhaust chamber and an exhaust stack, which together define an air passage having an inlet at the spray painting area and an outlet at the stack. A fan mounted in the stack draws air through the inlet and the working area at high velocity and discharges it through the stack. A plurality of generally vertical baffles are disposed in the passage between the spray painting area and the exhaust chamber for the purpose of removing overspray or excess atomized paint from the air before it is exhausted out of the stack. Mineral oil is continuously flowed over the front surface of the baffles so as to entrain therein paint solids carried by the air stream. The oil is received in a reservoir or holding tank wherein the paint solids are allowed to settle, and from which the oil is recirculated for flow over the baffles.
The mineral oil in the spray booth does not itself normally constitute a fire hazard because of its high flash point. Inherent in any paint spraying operation, however, is the possibility of fire, due principally to the flammable solvents found in many paint formulations. For this reason, existing governmental regulations and safety standards require the use of adequate fire control systems for spray booths.
A problem arises, however, if water spray or fog means are used in the interior of the above-described booth as a fire control medium. Since the oil reservoir is self-contained in the bottom of the booth, the water from the sprays would drain into the oil reservoir and displace the oil, causing the oil to spill out of the booth. Such occurrence would be undesirable from a safety viewpoint as well as from the standpoint of cleaning up a large amount of oil after the fire had been extinguished.